A mobile terminal (for example, a smartphone, PDA, tablet computer, etc.) is generally equipped with a display device such as a liquid crystal display or an organic electroluminescent display. Recently, an additional function such as a touch sensor function has been added to the display device.
In some liquid crystal display devices having the touch sensor function, a touch sensor is operated in blank periods of liquid crystal drive. Since a panel drive load in display drive periods (hereinafter referred to as display periods) is greatly different from that in sense periods of the touch sensor (hereinafter referred to as non-display periods) in this type of liquid crystal display device, a booster circuit and a regulator of the liquid crystal display device cannot follow a load change and noise is thus produced in a power source voltage. The noise may have various detrimental effects on the liquid crystal display device.